Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 21: Magnetic Shape Memory Alloys I

MA 21.3: Talk

Wednesday, March 25, 2009, 10:45–11:00, HSZ 103

Characterization of the transformation behavior of Fe-Pd ferromagnetic shape memory splats — •Iris Kock¹, Sven Hamann², Stefan Mayr¹, and Alfred Ludwig² — ¹Georg-August-Universität Göttingen, I. Physikalisches Institut, 37077 Göttingen, Germany — ²Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, 44780 Bochum, Germany

The Fe₇₀Pd₃₀ system is part of the promising new class of ferromagnetic shape memory alloys (FSMA). Fe₇₀Pd₃₀ shows a reversible martensitic transformation and a magnetic field induced strain (up to 3%) by detwinning of martensite variants (MFIS effect). In comparison to conventional SMAs the speed of actuation is not limited by heat conduction. If the material could be arranged as a freestanding thin film and showed this MFIS effect, it would be best suited for micro-actuator applications. Therefore freestanding Fe₇₀Pd₃₀ films were fabricated using the splat-quenching technique. Temperature-dependent changes in crystal structure (x-ray diffraction), resistance and magnetization of the splats were investigated. It was found that all three methods allow the determination of transformation temperatures. The results were used to investigate the influence of different post-annealing treatments on the martensitic transformation behavior of Fe₇₀Pd₃₀ splats. A significant increase of transformation temperatures with increasing post-annealing temperature was observed. The authors gratefully acknowledge funding by the DFG SPP 1239.